A conventional combustible gas turbine engine includes a compressor, a combustor, including a plurality of combustor units, and a turbine. The compressor compresses ambient air. The combustor units combine the compressed air with a fuel and ignite the mixture creating combustion products defining a working gas. The working gases are routed to the turbine inside a plurality of transition ducts. Within the turbine are a series of rows of stationary vanes and rotating blades. The rotating blades are coupled to a shaft and disc assembly. As the working gases expand through the turbine, the working gases cause the blades, and therefore the disc assembly, to rotate.
Each transition duct may comprise a generally tubular main body and a collar coupled to an exit of the main body. The transition ducts may be positioned adjacent to one another. The ducts may include brush seals held via holders coupled to the collars, metallic seal strips trapped in slots within the collars or labyrinth seals welded to or formed as part of the collars so as to prevent hot gases from passes between adjacent transition ducts.
The working gases produced by the combustor units are hot and under a pulsating pressure. The transition ducts are exposed to these high temperature gases and pulsating pressures, and vibrations can cause deflections in various locations of the tubular main bodies and collars. The transition duct is attached to the turbine engine at two points. The first attachment is at the top of the transition duct collar and an internal casing ring. The second attachment is at the inlet ring of the transition duct and the engine case pressure shell. Due the nature of holding a component in a dynamic flow condition with temperature gradients, stress failures may occur, for example, in corner portions of the tubular main bodies.